check which builder you're using first: go to service settings → build section

if using railpack (most likely): add this environment variable in your service variables tab:

RAILPACK_DEPLOY_APT_PACKAGES=ffmpeg

if using nixpacks: create nixpacks.toml file in your repo root:

toml

[phases.setup]
nixPkgs = ['...', 'ffmpeg']

then redeploy. ffmpeg will be in your system path

hope this help you

does it work as expected?

Thank you. It worked!

I had to enter the variable as you sent it through the raw editor is all. Otherwise couldn't get it to work.

i'm happy it works for you